Cementation process.



unrrnn 'srnarns FRIEDRICH ALBERT KAUFMANN, OF PERTH AIVIBOY, NEW" ERSEY, ASSIGNOR TO THE AT NT onisicn,

ROESSLER & HASS LAGHER CHEMICAL 00.,OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

- CEMENTATION PROCESS.

11,235,90ll. Specification of Letters Patent. No Drawing,

' 7 To all whom it may mm peror,

Be it known that I, FRIEDRICH ALBERT KAUFMANN, a subject of the German Emresiding at the city'of Perth Amboy Patented Aug. 7, 1191?,

a pneauon'mea August 11, 1915. seriamo. 44,951.

of treatment do not increase the depth of penetration of carbon in steel after reaching certain high temperatures by hydrocyanic in the county of 'Middlesex and State of' facidor other gaseous cyanogen compounds New 'Jersey, have invented certain new and useful (Improvements. in Cementation Processes, of wh'ch he following is a specification.

The invention relates to the cegnentation of iron, steel and ferrous alloys and has for its object to provide an improved process to render the operation more efficient and economical than heretofore.

The improvement achieved by my invention consists essentially inemploying hydrocyanic acid, in gaseous form, asfcementing agent forjron, steel and other ferrous alloys. Hydrocyanic acid is easily obtainable and has most perfectly the qualities necessary for cementation of steel; it is in gaseous condition at 26 ,C. and can be generated with the greatest ease from sodium cyanid,

otassium cyanid and similar cyanid' salts said gas from such cyanid salts. At an elevated temperature this gas decomposes into its constituents, of which the carbon is of especial interest for the purposes of casehardening or cementation, while the other constituents form ammonia which, as is well known, has a beneficial influence for the purpose in question. The carbon as formed by the decomposition of hydrocyanic acid, or by decomposition of other gaseous cyanogen compounds difiuses in the presence of inert gases formed in the course ofthe process of decomposition or purposely added,

more freely and easily. into the iron, steel and other ferrous alloys at a certain temperature, because it is then and is therefore more eflective than when under other conditions,

Owing to its catalytic properties, the presence of iron accelerates the decomposition of the gaseous cyanogen compounds.

- The effect of the carbon derived from the decomposition-of hydrocyanic acid or other gaseous cyanogen compounds is more pronounced and more satisfactory and quicker than the effect obtained with other gaseous cementing agents, bons, which as is well known,

cases, andwhich even after a long period sulfuric acid or any other mineral or or-' ganic acid of sufficient strength to generate u b6111 heated to a temperature above apin status nascendi', P

for instance, hydrocar-H form sudden however, that the application of hydrocy-,

anic acid derived by the reaction of cyanid salts with chemical compounds other than acids, 1s also within the scope of my invena certain depth. The treatment of steel at the;

tion. The hydrocyanic acid so generated is introduced by suitable devices, either alone or diluted by a suitable inert gas purposely added into a furnace containing the steel or other articles to be hardened, the furnace proximately "(00 C. The amount of gas and the length of time necessary for the process depends on the quality of hardening effect desired. The time may'vary from a few minutes to several hours according to the penetrationjof carbon to be obtained and the size of the steel or other articles to be. hardened. "Atfand above the aforesaid temperature the gas will quickly decompose and. the/carbon so formed being in status nascendi' and in the presence of lnert gases,

which inert gases may be decomposition products of the cyanogen compounds or may be purposely added, or both, will easily '7 enetrate the iron, steel or ferrous alloys to "the desired depth and in'the desired percentage. --After thus being hardened by my,

'new process thefurther treatment ofthe ,steel or other material can be carried on y theways well known to those skilled in the art. 3

Tclaim:

l. The process of cementing articles of iron, steel or ferrous alloys, consisting in treating said articles with gaseous hydrocyanic acid at an elevated temperature.

2. The process. of cementing articles of ironwsteel or ferrous alloys, consisting in treating said articles with gaseous hydro cyanic acid at an elevated temperature in the presence of inert gaseous matter.

3. The process of cementing articles of iron, steel or ferrous alloys, consistin in treating said articles at approximately 00 C. with gaseous hydrocyamc acid.

4. The process of cementing articles of iron, steel or ferrous alloys, consisting in decomposing gaseous hydrocyanic acid at approximately 700 G. into carbon and ammonia and acting with the nascent carbon on the articles. I

5. The process of cementing articles of iron, steelor ferrous alloys consisting in decomposing gaseous hydrocyanic acid at approximately 700 G. into carbon and ammonia and acting with the nascent carbon on the articles in the presence of the ammonia generated by the process.

6. The process of cementing articles of iron, steel or ferrous alloys, consistin in decomposing gaseous hydrocyanic aci at approximately 700 G. into carbon and ammonia and acting with the nascent carbon on the articles in the resence of the gen erated ammonia and ot er inert gases.

In testimony whereof I have signed this specification'in the presence of two subscribing witnesses.

' FRIEDRICH ALBERT KAUFMANN. Witnesses:

CATHERINE A. COSTELLO,- O'r'ro K. ZWINZENBERGER. 

